Method of identifying and treating invasive carcinomas

Abstract

Prostasin protein has been found to be a useful marker for determination of the invasiveness of and as a means to treat human carcinomas. Using RT-PCR and western blot analyses, prostasin protein and mRNA expression were found in normal human prostate epithelial cells and the human prostate cancer cell line LNCaP, but not in the highly invasive human prostate cancer cell lines DU-145 and PC-3. Imunohistochemistry studies of human prostate cancer specimens revealed a down-regulation of prostasin in high-grade tumors. Using RT-PCR and western blot analyses, prostasin protein and mRNA expression were found in a non-invasive human breast cancer cell line, MCF-7, while invasive human breast cancer cell lines MDA-MB-231 and MDA-MB-435s were found not to express either the prostasin protein or the mRNA. A non-invasive human breast cancer cell line, MDA-MB-453, was shown to express prostasin mRNA but not prostasin protein. Transfection of DU-145 and PC-3 cells with a full-length human prostasin cDNA restored prostasin expression and reduced the in vitro invasiveness by 68% and 42%, respectively. Transfection of MDA-MB-231 and MDA-MB-435s cells with a full-length human prostasin cDNA restored prostasin expression and reduced the in vitro invasiveness by 50% for either cell line.

We claim:  
     
       1. A method of determining human prostate carcinomas non-invasiveness using prostasin gene promoter DNA methylation levels, comprising the steps of: 
       sampling a human prostate carcinoma tissue;  
       determining prostasin gene promoter DNA methylation levels in the human carcinoma tissue; and  
       determining the human prostate cancer is not invasive based on the lack of DNA methylation of the prostasin gene promoter.  
     
     
       2. The method of  claim 1 , wherein the step of determining gene promoter DNA methylation levels includes: 
       applying prostasin-promoter-specific DNA probes in a southern blot hybridization analysis to determine the prostasin gene promoter DNA methylation levels in the sampled human prostate carcinoma tissue.  
     
     
       3. The method of  claim 1 , wherein the sampling comprises: 
       separating the human carcinoma tissue from the neighboring normal tissue by laser capture micro-dissection.  
     
     
       4. A method of determining human breast carcinomas non-invasiveness using prostasin gene promoter DNA methylation levels, comprising the steps of: 
       sampling a human breast tissue;  
       determining prostasin gene promoter DNA methylation levels in the human carcinoma tissue; and  
       determining the human prostate cancer is not invasive based on the lack of DNA methylation of the prostasin gene promoter.  
     
     
       5. The method of  claim 4 , wherein the step of determining gene promoter DNA methylation levels includes: 
       applying prostasin-promoter-specific DNA probes in a southern blot hybridization analysis to determine the prostasin gene promoter DNA methylation levels in the sampled human breast carcinoma tissue.  
     
     
       6. The method of  claim 4 , wherein the sampling comprises: 
       separating the human carcinoma tissue from the neighboring normal tissue by laser capture micro-dissection.